27. RELEASE FIRING DEVICE M1

a. Description. The Release Firing Device M1 is a nonelectric firing device designed to operate when a restraining load is removed from it. The device (fig. 22) measures ap-proximately 2 7/8 by 1 7/8 inches, and consists of a cube-shaped body containing the lever, spring, and firing pin, mounted on a nailing bracket. The end of the body is provi-ded with a female connection to take the standard firing device base used in the other types of firing device. The firing mechanism consists of the latch, spring lever, spring, and firing pin. The latch normally is held in position by the safety pin. Two 3/16-inch diameter holes are provided on the sides to permit the insertion of a nail or stiff wire to act as an auxiliary safety device by blocking the spring lever from striking the firing pin. When cocked, the device is restrained from firing as long as there is at least a 2-pound load on the top face of the latch. A nailing is provided by a thin plate ¾ of an inch wide by 4 inches long, spot-welded to the bottom of the body.

Figure 22 - Release Firing Device M1

b. Functioning. In order to remove the safety pin, a weight of at least 2 pounds must be applied to the exposed surface of the latch. After the safety pin is removed, the re-moval of the load on the latch automatically frees the spring lever which, propelled by the spring, swings through and strikes the firing pin at the end of its flight, firing the percussion cap and detonating a nonelectric cap crimped to the base.

c. Installation. Prepare and place the mine charge as for the other firing devices (par. 24 c (2).

(1) Slide the open end of a nonelectric cap over the projection on the base and crimp, using cap crimpers. This should be done carefully to insure a tight crimp and a water-proof joint between the base and the blasting cap.

(2) Provide a level, solid foundation on which the device is to rest. If a board is avail-able, utilize it as a foundation and nail the device to it.

(3) Be sure the safety pin is in place. Insert a nail or wire through the side holes as an additional safety device.

(4) Screw the base with the blasting cap attached, into the device.

(5) Insert the blasting cap in the charge.

(6) Place the restraining load (antitank mine, heavy book, etc.) on the explosed surface of the latch.

(7) Remove the safety pin and then the additional safety device (nail or wire). Be care-ful not to disturb the restraining load.